In the field of orthodontic treatment, it is sometimes necessary to extract one or more teeth prior to tooth repositioning. In some treatment cases, patients have previously had one or more teeth removed, also leaving a void or space between teeth. Also it is possible, in some cases, for an abnormal space to exist between two neighboring teeth due to irregular growth of one or more teeth. To fill the void when a tooth aligner is utilized, an artificial tooth or other structural component is used which is commonly referred to as a dental pontic. The ability to utilize such pontics during orthodontic treatment is desirable in these orthodontic applications, with such pontic cases comprising approximately 10% of all treated orthodontic cases.
In the case of polymeric shell aligners, the dental pontics used are different from the traditional physical dental pontic, which is an actual physical pontic positioned on the patient arch. In contrast, dental pontics are herein utilized to control the forming of pontics in polymeric shell aligners. For example, the design and fabrication of dental pontics is disclosed in U.S. Pat. No. 6,790,035, entitled “Method and Kits for Forming Pontics in Polymeric Shell Aligners” and assigned to Align Technology, Inc. For example, in such applications, a polymeric shell dental appliance that is removably placeable over a patient's dentition. The clinician manually determines the location in the appliance where the tooth is missing, as well as visually determining the size, position and shape characteristics of the space between teeth, e.g., the height, width, depth, contour, surface and like characteristics. After the space (or spaces) is identified, one pontic (or more pontics) is formed by filling the space within a trough of the appliance with a material, such as curable silicone compositions, to resemble a tooth.
As one would appreciate, the width and shape of the space between teeth gradually decreases or increases during various stages of treatment, thus requiring a process of manually determining the space or gap characteristics, such as size, shape and position, to provide an updated pontic geometry. Such manual determination is labor and time intensive and is subject to difficulties in making changes to pontic parameters when reviewing pontic geometries. In addition, the explicit and practicable methods utilized to construct the parametric pontic, in terms of representation and modeling, are very critical for forming polymeric shell aligners.